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    • DeltaWave vs Wave Corrector

    visualizing differences betweeen music files before and after tick removal

    What

    Wave Corrector selectively removes suspected tick and pops from LP recordings;
    DeltaWave analyzes differences between music files, in this case before and after Wave Corrector    .

    While it may seem obvious that audio signals with no difference will be indistinguishable,
    there is actually some data to confirm that.
    Double-blind testing is considered by many the best basis for audio preference,
    but there are to my knowlege few individuals with a track record of being good at it.
    "Sterephile" founder J. Gordon Holt is one of that few that could and did:

    "As far as the real world is concerned, high-end audio lost its credibility during the 1980s,
 when it flatly refused to submit to the kind of basic honesty controls (double-blind testing, for example)
 that had legitimized every other serious scientific endeavor since Pascal.
 [This refusal] is a source of endless derisive amusement among rational people and of perpetual embarrassment for me,
 because I am associated by so many people with the mess my disciples made of spreading my gospel.
 For the record: I never, ever claimed that measurements don't matter.
 What I said (and very often, at that) was, they don't always tell the whole story. Not quite the same thing."
 45 Years of Stereophile
    Regardless, in the Carver Challenge, he was unable to distinguish two very different amplifier designs,
    one of which by null testing had been tweaked to match the other.

    The track here is "Jesse" from Joan Baez' "Diamonds and Rust" half-speed mastered Nautilus LP.
    This record had been cleaned by a Keith Monks machine and StyLast treated before first playing, 40+ years ago.
    Some younger CDs are no longer playable...
    Neither ticks nor pops were noted while recording,
    but Wave Corrector identified anomalies that seem credible blemishes.
    Wave Corrector was run with default settings, except threshold reduced from 3 to 1.
    It incorrectly identified several quiet interludes in the song as track breaks;  those were corrected.
    About 27 seconds of mistracking were recorded at the song start and deleted in the deticked copy.
    DeltaWave was unable to match tracks until setting Trim Front: 25 sec;
    remaining trash presumably threw off difference metrics.

    Speed up trim trials

    Double-clicking th End option allows specifying seconds to Show.  (30 works for 96kHz):

    Once Trim front value is found by trial and error, viewing overlaid waveforms,
    then double-click Take back to End [ 0].

    Explanation:
    Ah, the problem is that there are more than one points where large portions of the two files can align really well.
    DeltaWave can't tell where the alignment points are and guesses that it's a periodic waveform
    (one that has at least a few repeating sections, such as a sinewave, for example).
    DW has a different algorithm for dealing with such files, so it offers you to do so.
    You don't have to agree to treat it as a simple waveform, but you will be warned.
    Here are unalighed waveforms:

    .. then aligned spectra:

    As hoped, waveforms differ only when ticks are corrected:

    I suppose that a lack of phase differences above 13kHz implies lack of energy:

    As with waveforms, spectrogram delta shows differences only for removed ticks:

    X-axis time stamp variations were unexpected
    Linearity spikes are presumably also tick removal artifacts:

    Superficial understanding of PK Metric suggests audibility of 2 tick corrections.

    The DF metric suggests something should be rarely audible;
    that may be from the vestigal 2 first mismatched seconds:

    Camera icon at lower left was not noticed until the final screen capture...
    According to developer pkane, PK dBr better corresponds to audibility:


    -   18 Apr 2023

    maintained by blekenbleu